1. Field of the Invention
The present invention relates to wood and iron golf clubs and, more particularly, to means for reinforcing wood and iron golf club heads.
2. Description of the Prior Art
It is understood by those in the art that the term "woods" pertains to a family of golf clubs having shafts of longer length, used primarily for tee and fairway shots where considerable distance is the object. "Iron" clubs are those of shorter length, generally employed for shorter distances. For various reasons, woods with club heads made of wood materials are being superceded by heads made of metal or of composite graphite or other materials. Metallic heads are usually hollow in construction, to produce a head with volume large enough for practical use. Because the density of metallic materials is so high, solid club heads of adequate volume are prohibitively heavy. While most composite graphite club heads to date have been of solid construction, recent designs for these club heads have also incorporated hollow interiors. In any case, composite graphite heads generally include separately attached sole plates, usually made of steel, aluminum or brass.
In the case of iron club heads, these club heads have traditionally been solid. However, hollow iron club heads have been available for about two decades.
Hollow woods and irons have met with several difficulties. In many cases, the striking faces of the heads can not withstand impact forces over time, resulting in denting or face collapse. In other cases, the club head distorts excessively during impact with the ball, due to compressive forces. In the case of hollow club heads employing thicker club faces, concentration of club head weight at the face necessitates making the rest of the club head with thinner walls to keep the club head at the desired weight. Crumpling and fracturing of these thinner wall surfaces has occurred at undesirable rates.
Injection molded composite graphite heads have tended to be too soft for the application, yielding a poor energy transfer from head to ball. Harder material inserts, located in the striking face at the impact zone, have been a general remedy, but overall head distortion during head-ball collisions is still high. Compression molded composite graphite solid heads have tended to resist impact forces well, but the comparative cost of compression molded heads is too high.
The prior art has sought to overcome these difficulties with several remedies, including attempted reinforcement of head faces on the interior of the face wall to resist face collapse. See, for example, U.S. Pat. Nos. 3,847,399 and 4,930,781.
U.S. Pat. Nos. 4,076,254; 5,000,454; 4,535,990; 4,313,607; 4,756,534, 4,681,321; and 1,658,581 generally disclose a support member in the club head interior extending from the interior side of the club striking face to the rear of the club. Other designs utilize special alloys, including cobalt, to improve club head strength. None of the above utilize the structural properties of triangulation to advantageously resist deformation and enlarge the sweet spot of the striking face.
Thus, it is an object of the present invention to increase mechanical stiffness and strength in the golf club head so that the head will resist deformation at impact with a golf ball. It is a further object to provide added mechanical strength to the striking face of the club, so that the face thickness can be safely reduced. It is a still further object to reduce face wall thickness to liberate a finite amount of weight which can then be added to other portions of the club head to serve other design criteria, such as relocating the center of gravity to more optimum locations. It is a still further object to provide resistance to twisting of the club head at impact with the ball to reduce deviation of the ball from the intended target line. With respect to composite graphite heads, it is an object of the invention to enable use of relatively inexpensive injection molding to form the heads without compromising head strength. Finally, it is an object of the present invention to enlarge the "sweet spot" hitting zone of the striking face.